Abu Huraira reported Allah's Messenger (may peace be upon him) as saying: Do not greet the Jews and the Christians before they greet you and when you meet any one of them on the roads force him to go to the narrowest part of it. (Sahih Muslim, Book 026, Number 5389)
For more on the ambivalent relationship of Muhammad to Christians, see these articles:
The Quranic View of Christians
— Fellow Believers or Unbelieving Polytheists?
How to Greet Nonbelievers According to the Quran and Sunna
See also the entry on CHRISTMAS.
an-Nisa' 4:86; al-Furqan 25:63